The philosophy of short stem prostheses involves load transfer close to the joint, which means that the bone substance can be preserved as well as possible in the long term. Originally, short stem prostheses were developed for young and active patients. In recent years, however, due to excellent results and a number of advantages compared to conventional prostheses, their use has been increasingly extended to all other patient groups.
Artificial hip joints have been used successfully in Germany for many decades. The number of short-shaft prostheses has risen continuously in recent years and already amounted to over 12 percent in Germany in 2022 . This type of prosthesis is becoming even more widespread across Europe.
The short stem prosthesis is a special type of hip prosthesis and belongs to the group of total hip endoprostheses(hip TEP).
When a short stem prosthesis is implanted, the hip socket in the pelvis is also replaced. The special feature of the short stem prosthesis, however, is that only a small part of the femoral neck usually has to be removed in the area of the femur. The remaining femoral neck and the upper part of the femur are used to anchor the shorter prosthesis stem.
A short stem prosthesis as an artificial hip joint affects less bone material than other forms of hip TEP © Mathys, Switzerland
Treatment of hip osteoarthritis(coxarthrosis) usually begins with conservative measures. These include
- Physiotherapy,
- painkillers and
- weight loss if necessary.
If these measures do not alleviate the symptoms, an artificial hip joint may be considered in cases of advanced hip osteoarthritis.
For most people, the artificial joint provides significant and long-term pain relief. It also increases mobility and mobility again.
Artificial hip joints prove to be very durable. Around 95 percent of all hip prostheses are still intact ten years after the operation. Between 85 and 90 percent are still in the body and functioning well even after more than 20 years.
The younger a patient is when a hip prosthesis is fitted, the greater the likelihood that a replacement operation will have to be performed later. With young patients, it therefore makes sense to preserve as much bone as possible during the first operation in view of later prosthesis replacements. This can be achieved with a short stem prosthesis. This prevents problems during a later replacement operation.
However, good bone quality is aprerequisite for the use of a short stem prosthesis. A short stem prosthesis is associated with a smaller anchoring surface in the bone and places a higher load on it.
More natural loading of the bone: The shorter stem and the fixation close to the joint improve the loading of the bone, which leads to better preservation of the natural bone structure in the long term.
High stability: The special guide along the femoral neck ensures precise placement of the stem and high stability of the prosthesis.
Less tissue damage: The insertion of short stem prostheses usually requires a smaller incision and less tissue damage than ordinary hip prostheses. Due to their round design, short stem prostheses can be used much better in conjunction with minimally invasive approaches. This can lead to faster recovery, less bleeding and less pain.
Improved mobility: The precise placement along the anatomy and the more natural loading of the bone can improve the mobility of the hip joint.
Reduced risk of complications: Short stem prostheses have a lower risk of complications such as popping out of the joint as well as fractures compared to traditional hip replacements.
Shorter hospital stays: Due to less tissue damage and therefore often faster recovery, patients who receive short stem prostheses can typically have shorter hospital stays.
A short-shaft prosthesis is inserted under general or partial anesthesia. The operation takes around 45 to 90 minutes.
With the short stem prosthesis, a minimally invasive approach to the hip is perfectly feasible, which is particularly gentle on the tissue. The surgeon makes a small incision in the front or front-side of the hip joint.
Even more important than the short incision is the protection of the muscles and tendons surrounding the hip joint. This tissue protection often has various advantages, such as
- Less blood loss during the operation,
- less pain after the operation and
- faster rehabilitation.
First, the surgeon removes the femoral head and mills out the acetabulum. He then attaches the prosthesis cup in the pelvis and then the prosthesis stem (hip stem) in the thigh bone. An artificial ball head is placed on top. This should be made of ceramic due to its good properties in terms of long-term durability.
Short stem prostheses are usually fixed"cement-free", i.e. they are initially clamped in the upper, still intact femur. This gives them what is known as primary stability. In the weeks following the operation, they grow into the bone tissue, which further increases stability. This is referred to as secondary stability.
Before stitching up the wound, the doctors take an X-ray to check the fit of the prosthesis.
This procedure ensures that the prosthesis fits perfectly and that the operation has the maximum chance of success.
Short stem prostheses with cemented anchoring for patients with limited bone quality have also been available on the market for several years. However, a final assessment of the safety and reliability of these cemented short stems is still pending.
A short stem prosthesis is usually implanted without cement © Prof. Dr. med. Karl Philipp Kutzner
As a rule, full weight-bearing of the operated joint is possible immediately after the short stem prosthesis has been implanted. The patient can usually stand up for the first time and take their first steps on the day of the operation. The physiotherapy exercise program for the hip joint begins in the first few days after the operation. The hospital stay today often only lasts around 2-3 days.
The treatment goals after the operation are
- to enable the patient to stand up and walk independently,
- increasing mobility and
- climbing stairs.
Forearm crutches are usually used for this. As the implants are usually cement-free, impact loads and maximum strength exercises in particular should be avoided in the first few weeks so as not to jeopardize trouble-free ingrowth.
Every surgical procedure as part of a hip joint replacement has general surgical risks. The anesthesia also contributes to this.
In rare cases, the use of an artificial hip can result in fractures or tears in the thigh. This risk is slightly increased with cementless prostheses, such as the short stem prosthesis. In this case, additional stabilization of the bone may be necessary and a different type of prosthesis must be used. Stabilization is achieved with wire loops, screws or metal plates, for example.
Only very rarely do muscle injuries or bleeding occur during the surgical procedure that require a blood transfusion.
It can also lead to
may occur. Patients receive an antibiotic against inflammation during the operation. Anticoagulant medication in the form of injections or tablets is also administered in the weeks following the operation. These serve to prevent thrombosis.
There is also the rare possibility of ossifications developing around the artificial joint after the operation. These ossifications restrict the mobility of the prosthesis. To prevent this from happening, patients take anti-inflammatory painkillers for around two weeks, which also work against ossifications.
There is also an unlikely risk of dislocation, i.e. the femoral head popping out of the socket, in the first few weeks after the operation. Dislocation is painful. In most cases, however, the femoral head can be repositioned without further surgery. However, in some cases further surgery is necessary. As short stem prostheses are usually better able to reproduce the anatomical conditions than conventional implants, there is a significantly lower risk of such dislocation.
Nevertheless, it is advisable to be cautious at first and to avoid certain movements in the first six weeks after the operation and to use aids for certain activities. This will be explained, practised and organized for you during your inpatient follow-up treatment.
Although short-shaft prostheses are still a relatively new type of prosthesis, we can now draw on over 10 years of experience and corresponding scientific data. In addition to the numerous advantages that are due to the shorter, rounder shape of these prostheses, the results of the numerous implant registries worldwide in particular show excellent results for a large number of short stem prostheses. These are among the safest and most reliable implants in the first few years. The rate of re-operations or complications, such as loosening, is significantly lower than for conventional stem models.
The implantation and anchoring philosophy of short stem prostheses differs from conventional hip stems. The surgeon's experience with modern short stem prostheses therefore plays a decisive role for patients. Sound advice from a short stem specialist in the run-up to a hip joint replacement contributes significantly to a successful procedure and an excellent surgical result.
In Germany, the short stem prosthesis is now an established component in the replacement of hip joints with good bone quality. It has numerous advantages with a manageable risk. It is to be expected that this type of prosthesis will become increasingly popular in the future. As the technique and philosophy differs from other hip implants, a great deal of experience with short stem prostheses is crucial. You should therefore consult an appropriate specialist for short stem prostheses.
